1. Field of the Invention
This invention relates to a system capable of remote validation of the identity of an individual.
2. Description of Related Art
Remote validation of the identity of an individual for access control is an age old problem that has many different solutions. The oldest and most common solution has been to issue a metal key to the valid user. The detailed shape of the key contains coded information. However, keys can be lost, stolen or duplicated and given to others, thereby compromising security.
The use of electronic identification cards such as credit cards with electronic or magnetic data codes for access control purposes has similar drawbacks. Credit cards can also be lost, stolen, and/or duplicated. For some financial transactions using credit cards, the coded information in the card must be complemented by a personal identification number (PIN) that the user is advised to commit to memory. This is so that a lost card will be of no value to anyone but the valid user. In practice, however, a substantial fraction of credit card users find it difficult to remember their PIN number, and therefore write it down on a slip of paper that they carry in their purse or wallet. If a thief steals a wallet or purse, he not only gets the credit card, but also the PIN as well.
In the case of remote identity validation for the purpose of "electronic house arrest," neither electronic identification cards nor keys are useful. While numerous remote validation systems have been proposed, each has significant drawbacks. Nevertheless, the demand for such systems is continually increasing.
The rapid growth in the field of electronic monitored house arrest is being propelled by several key factors, including the limited capacity of existing penal institutions, the substantial growth in crime rate and conviction rate in most major metropolitan areas, increasing taxpayer reluctance to bear the expense of expanded jail or prison facilities, resistance by citizen groups to the construction of new penal institutions in their neighborhoods, recognition that many convicted offenders do not represent a risk to society, so that incarceration is an unnecessary and expensive alternative to house arrest, and a growing awareness that electronic house arrest is the most cost effective alternative to effectively manage and monitor offenders who are not dangerous to society. A basic economic reality is that new prison facilities cost approximately $50,000 per prisoner to construct and approximately $50-60 per day to operate. In contrast, electronic house arrest can be provided for about $4 per day or less and, in many cases, the offender is willing to pay this fee for the privilege of not being incarcerated.
A number of electronic house arrest products have been introduced to the market in the past several years. At one extreme is a rather primitive system introduced by Digital Products Corporation, Inc. that requires the offender to wear a coded device on his or her wrist. The device is inserted into a special attachment on a telephone for verification, as described in U.S. Pat. No. 4,747,120. The system reliability depends primarily on the ability of a parole officer to recognize the voice of the offender when random telephone calls are made to the officer. This is because the wrist-worn device can be removed and left for someone else to insert into the telephone verifier while the offender is gone.
At the other extreme, there are very costly systems such as the video monitoring systems offered by Matsushita. This system can grab a single video picture of the offender and relay it over the telephone lines to a parole officer in approximately one minute. The offender is asked to do something recognizable such as "touch your left ear", in order to avoid use of a photograph positioned in front of the video camera.
The most popular type of system on the market today employs a coded radio transmitting device that is attached to the offender's ankle or wrist. The radio transmitter automatically sends a periodic coded signal to a receiver module attached to the offender's telephone. If the signal is not received, the receiver module automatically dials the parole officer to report a violation. Alternatively, the receiver module can be periodically interrogated for recent violations by an automatic telephone response device located in the parole officer's facilities. To enhance security against tampering, the radio transmitter is designed to stop functioning if it is removed from the offender's wrist or ankle. This type of radio equipment is available from BI Inc. and Digital Products, Inc. and is described in Pat. No. 4,747,120 to Foley, for example. Such systems have a history of problems that relate to various interferences that can disrupt the radio link. For example, if the offender walks behind a metal object, such as a refrigerator, or enters a room with metal foil wallpaper, the radio signal can be lost. This could trigger an investigation which is both expensive and undermines confidence in the system.
All of the current electronic house arrest systems require some attachments to an offender's telephone. This is even true for a voice recognition system capable of validating the presence of an offender by his electronic voice print in analogy with a finger print. Voice recognition could, in principal, be performed at a remote station without additional attachments to the telephone of a person being monitored. However, in practice, the low fidelity of a voice transmitted over the telephone system is not of sufficient quality for consistent and reliable detection. Thus, voice identification equipment must be located in the residence of the person being monitored with an attachment to the telephone. In addition to being expensive, voice recognition equipment is notorious for failing when the offender has developed a cold or congestion which alters his "voice print".